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Prefer stable types to diagnose useless cast

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#KT-11622 Fixed
This commit is contained in:
Mikhail Zarechenskiy
2017-04-05 05:47:34 +03:00
parent 13eddba1f2
commit f518e8ebb8
7 changed files with 64 additions and 25 deletions
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compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
+18 -15
View File
@@ -375,30 +375,34 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
context.trace.report(CAST_NEVER_SUCCEEDS.on(expression.getOperationReference()));
return;
}
KotlinTypeChecker typeChecker = KotlinTypeChecker.DEFAULT;
if (isExactTypeCast(actualType, targetType)) {
// cast to itself: String as String
if (castIsUseless(expression, context, targetType, actualType, typeChecker)) {
context.trace.report(USELESS_CAST.on(expression));
return;
}
Collection<KotlinType> possibleTypes = components.dataFlowAnalyzer.getAllPossibleTypes(
expression.getLeft(), context.dataFlowInfo, actualType, context);
boolean checkExactType = shouldCheckForExactType(expression, context.expectedType);
for (KotlinType possibleType : possibleTypes) {
boolean castIsUseless = checkExactType
? isExactTypeCast(possibleType, targetType)
: isUpcast(possibleType, targetType, typeChecker);
if (castIsUseless) {
context.trace.report(USELESS_CAST.on(expression));
return;
}
}
if (CastDiagnosticsUtil.isCastErased(actualType, targetType, typeChecker)) {
context.trace.report(UNCHECKED_CAST.on(expression, actualType, targetType));
}
}
private static boolean castIsUseless(
@NotNull KtBinaryExpressionWithTypeRHS expression,
@NotNull ExpressionTypingContext context,
@NotNull KotlinType targetType,
@NotNull KotlinType actualType,
@NotNull KotlinTypeChecker typeChecker
) {
Collection<KotlinType> possibleTypes = DataFlowAnalyzer.getAllPossibleTypes(expression.getLeft(), actualType, context);
KotlinType intersectedType = TypeIntersector.intersectTypes(typeChecker, possibleTypes);
if (intersectedType == null) return false;
return shouldCheckForExactType(expression, context.expectedType)
? isExactTypeCast(intersectedType, targetType)
: isUpcast(intersectedType, targetType, typeChecker);
}
private static boolean shouldCheckForExactType(KtBinaryExpressionWithTypeRHS expression, KotlinType expectedType) {
if (TypeUtils.noExpectedType(expectedType)) {
return checkExactTypeForUselessCast(expression);
@@ -414,7 +418,6 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
}
private static boolean isUpcast(KotlinType candidateType, KotlinType targetType, KotlinTypeChecker typeChecker) {
if (KotlinBuiltIns.isNullableNothing(candidateType)) return false;
if (!typeChecker.isSubtypeOf(candidateType, targetType)) return false;
if (isFunctionType(candidateType) && isFunctionType(targetType)) {
compiler/frontend/src/org/jetbrains/kotlin/types/expressions/DataFlowAnalyzer.java
+2 -3
View File
@@ -1,5 +1,5 @@
/*
* Copyright 2010-2015 JetBrains s.r.o.
* Copyright 2010-2017 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -344,13 +344,12 @@ public class DataFlowAnalyzer {
@NotNull
public static Collection<KotlinType> getAllPossibleTypes(
@NotNull KtExpression expression,
@NotNull DataFlowInfo dataFlowInfo,
@NotNull KotlinType type,
@NotNull ResolutionContext c
) {
DataFlowValue dataFlowValue = DataFlowValueFactory.createDataFlowValue(expression, type, c);
Collection<KotlinType> possibleTypes = Sets.newHashSet(type);
possibleTypes.addAll(dataFlowInfo.getStableTypes(dataFlowValue));
possibleTypes.addAll(c.dataFlowInfo.getStableTypes(dataFlowValue));
return possibleTypes;
}